Adjustable magnetic trip circuit breaker



March 5, 1968 F, E, MYERS 3,372,354

ADJUSTABLE MAGNETIC TRIP CIRCUIT BREAKER Filed Oct. 7, 1966 3 Sheets-Sheet l #fram/fyi l Filed Oct. 7, 1966 March 5, 19-68 F. E. MYERS 3,372,354

ADJUSTABLE MAGNETIC TRIP CIRCUIT BREAKER 5 Sheets-Sheet 2 March 5, 1968 F. E. MYERS 3,372,354

\ ADJUSTABLE MAGNETIC TRIP .CIRCUIT BREAKER Filed Oct. 7, 1966 5 Sheets-Sheet 5 United States Patent @dice 3,372,354 ADJUSTABLE MAGNETIC TRIP CIRCUIT BREAKER Felix E. Myers, Haddon Heights, NJ., assigner to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of lPennsylvania Filed Oct. 7, 1966, Ser. No. 585,162 9 Claims. (Cl. 335-176) My invention relates, in general, -to magnetic trip circuit breaker devices, and more particularly to a novel means of adjusting the armature air gap and thereby Calibrating the tripping point.

Circuit breaker devices generally include a pair of cooperating contacts and an operating mechanism for moving the vcontacts between contact engaged and contact disengaged conditions. The operating mechanism is automatically activated by a circuit responsive trip means for effecting rapid disengagement of the contacts responsive to predetermined circuit conditions. In typical circuit .breakers having a magnetically actuated instantaneous trip, an armature is movable towards the pole faces of a cooperating magnet means responsive to the electromagnetic energization thereof reaching a predetermined value. The movement of the armature towards the cooperating magnet typically serves to release a latch, whereby the operating mechanism of the circuit breaker moves the cooperating contacts to their TRIP condition. Calibrated adjustment of the energization required to move the armature towards its magnet is generally obtained by adjusting the air gap separation between the armature and magnet pole faces. My invention relates to an improved arrangement for effecting such an air gap adjustment, while simultaneously controlling the operating mechanism latch bite.

The illustrative embodiments of my invention are shown in conjunction with a circuit breaker mechanism of the general type shown in my U.S. Patent No. 2,996,589, issued Aug. 15, 1961, entitled, Pivoted Bimetal, and assigned to the assignee of the instant invention. Such a circuit breaker mechanism has achieved widescale utilization for home and light industrial use, `and has advanced to the point where it is extremely reliable and efficient in operation, and may be rapidly and economically manufactured. While the circuit breaker mechanism shown in my aforementioned patent shows both an instantaneous magnetic trip and a time delayed thermal trip, it is oftentimes desirable to provide a magnetic trip only. An external adjustment should preferably be providedjfor circuit breaker calibration. Advantageously, my invention providessuch anexternal adjustment which utilizes portions of the previously provided thermal calibration means, thereby minimizing the extent of circuit breaker component or housing re-design.

The operating mechanism of such circuit breakers generally includes alatchable cradle member, which engages a latch tip means, carried by an elongated pivoted member. An operating spring urges the latchable cradle member from its latched position to a second position. As long as the latching engagement is maintained between the cradle member and the latch tip member, the circuit breaker contacts will be maintained in their engaged position. The electromagnetic trip means for releasing this latching engagement includes an armature. As the armature moves towards its-cooperating magnet means, a tripping means portion thereof strikes a trip portion of the latch, thereby unlatching the cradle. In order to insure sucient momentum for reliable operation of the latch, a predetermined trip spacing should be maintained between the armature actuated tripping means and the trip portion of the latch. This condition should be main- CFI 3,372,354 Patented Mar. 5, 1968 tained under all conditions of armature air gap adjustment.

Advantageously, my invention satisfies this requirement by adjusting the armature air gap with a member secured to the end of the elongated pivoted member which carries the latch tip and trip portion. Calibrated adjustment of the armature requires pivoted movement of the elongated latching member, thereby simultaneously moving the trip portion thereof. Hence, as the armature air gap is varied, the trip spacing between the portion of the armature Iwhich strikes the latch member and said latch member will be maintained.

It is therefore seen that a primary object of my invention is to provide an improved magnetic trip adjustment for a circuit breaker mechanism.

A further object of my invention is to provide a magnetic trip adjustment for a circuit breaker device, which includes means for simultaneously controlling the trip spacing between the armature and latch means over a predetermined range of armature air gap adjustments.

An additional object of my invention is to provide an improved adjustable electromagnetic trip for a latchable circuit breaker mechanism in which the distance between the armature and latch member is maintained substantially constant over a predetermined range of armature air gap adjustments.

Another object of my invention is to provide an improved adjustable electromagnetic trip for a latchable circuit breaker mechanism, which includes a pivoted elongated member, having an armature adjustment means mounted to its latch tip end.

Still a further object of my invention is to provide such an improved adjustable electromagnetic trip adjustment, wherein the armature adjustment means comprises a resilient member having a first portion mounted to the latching end of the pivoted elongated member and a second portion in engagement with the armature.

These, as well as other objects of my invention, will become readily apparent upon a consideration of the following descriptions and drawings in which:

FIGURE l is a front View, with the cover removed, of a magnetic trip circuit breaker mechanism, shown in the contact engaged condition, and utilizing the improved adjustment structure of my invention.

FIGURE 2 is an exploded perspective view showing the electromagnetic trip, latching and adjustment portions of the circuit breaker device.

FIGURE 3 shows the magnetic trip and armature adjustment portions of a circuit breaker corresponding to a particular armature adjustment.

FlGUl-E 4 showsl the magnetic trip and armature adjustment portion after it has undergone calibrated adjustment for reducing the air gap separation between the armature and its cooperating pole face.

FGURES 5 and 6 are front elevation and side views, respectively, of the pivoted elongated member of my invention.

FIGURE 7 shows the novel armature adjustment mechanism of my invention in association with a slightly different means of external actuation.

Circuit breaker 10, which is shown including the improved adjustable magnetic trip structure in accordance with my invention, is of the general type shown in my aforementioned U.S. Patent 2,996,589. The electromagnetic trip structure 5t) thereof is generally of the type which is the subject of my co-pending U.S. patent application Ser. No. 495,526, tiled Oct. 13, 1965 now Patent No. 3,319,196, and entitled, Electromagnetic Structure. It should naturally be understood that the broad concepts of my invention may be practiced in conjunction with other circuit breaker mechanisms and electromagnetic trip structures, with this particular embodiment being principally shown for illustrative purposes.

Circuit breaker is housed within a molded insulative housing 11, which includes a plurality of recesses for receiving and locating the various operating components thereof. The open side of casing 11 is capped by a removable cover (not shown) which is also constructed of a molded insulative material, and which is secured to base 11 by rivets 21 which pass through aligned apertures of the base and cover. Located within housing 11 is a stationary contact 22, which is electrically connected via conductive member 24 to line terminal 26, which is illustratively shown as a screw-type terminal. It should, however, be understood that a plug-in type terminal may be substituted therefor. Cooperating with stationary contact 22 is a movable contact 26 which is mounted at the lower end of movable contact arm 27. Parallel plate arc extinguishing means 99 may be provided within recesses 161 on the circuit breaker molded housing. The upper bifurcated end of contact arm 27 abuts a suitable pivot formation of internally extending portion 28 of manual operating member 15. Manual operating member 15 is pivoted about a protrusion 14 thereof which is entered into suitable aligned recesses of the base 11 and cover, and includes an outwardly extending end portion 16 for manually moving the circuit breaker between its manual OFF and manual ON positions, in the manner fully set forth in my aforementioned U.S. Patent No. 2,996,589.

Contact carrying arm 27 has a braid member 58 secured thereto, with the opposite end of the braid member being connected to one end 115 of the electromagnetic actuating coil 106 (see FIGURE 2). The opposite end 112 of the electromagnetic actuating coil is connected to the load terminal 62. Thus, the current carrying path through the circuit breaker 10 begins at the line terminal 26 thereof, through conductive member 24 to stationary contact 22 to complimentary moving contact 26, contact arm 27 and braid 53 through electromagnetic trip coil 106 and terminating at load terminal 62. Thus, it is seen that the electromagnetic actuating coil is in the series path of current load through the circuit breaker 10, and hence, the electromagnetic actuation of magnetic trip means 50 will be proportional to circuit current.

The operating mechanism for bringing about the engagement and disengagement of the cooperating contacts 22, 26 further comprises a latchable cradle member 31 which is pivotally mounted at one end thereof to base protrusion 32 and forms a latch tip 34 at its opposite end. Cradle 31 also carries a kicker 38. One end of an operating spring 33 is connected to cradle 31 at aperture 29 intermediate the ends thereof, while the other end of spring 33 is connected to contact arm 27 and aperture 29. Operating spring 33 is always in tension, thereby urging Contact arm 27 upwardly into engagement with its pivotal mounting to manual operating member 15 and latchable cradle member 31 clockwise about its pivotal mounting 32. The force of operating spring 33 relative to the pivotal mounting of contact arm 27 serves to urge the movable contact 26 into firm engagement with its cooperating stationary contact 22.

Latchable cradle member 31 includes a latchable tip 34 which seats upon latch portion 35, carried by the lower end of elongated latch means member 36. Latch portion 35 is shown as a generally L-shaped member which is secured to the lower end of elongated member 36 by rivet member 37, extending through an aperture at the lower end thereof. Rivet 37 also secures the resilient armature adjustment member 6i) to elongated member 36 for purposes which will henceforth be described.

A bearing pin 41 is suitably secured to an intermediate region of elongated element 36, as by welding, and enters suitable circular recesses of the circuit breaker base 11 and cover for pivotally mounting the elongated element 36 thereto. Elongated member 36 is biased in a clockwise direction by spring 70 which is disposed in recess 72 of base 11, with one end of the spring 70 abutting the internal wall of the recess and the other end of spring '70 abutting the upper end of elongated member 36 above its pivotal mounting 41. In accordance with this embodiment of my invention, calibrated adjustment of the magnetic trip is obtained by externally accessible adjusting screw 74 which extends through an opening 79 in base 11 and is received by nut 76 disposed in a suitable recess 81 of the base. End '78 of screw 74 abuts one leg of a tensioning member 80, thereby forcing the end 83 of tensioning member against the upper end of elongated member 36, against the force of spring 70, so as to calibratingly move the elongated member about its pivot 41.

The electromagnetic structure 50 which may be of the general type shown in my aforementioned U.S. patent application Ser. No. 495,526 includes a bobbin having side walls 116, 118 and a central core portion 114. Actuating winding 106 is wound about core portion 114 with one end thereof being connected to braid 58. The opposite end 112 of the energizing coil is connected to load terminal 62. Upper and lower locating protrusions 121, 123 outwardly extend from the respective side walls 116, 118 of the bobbin assembly and are positioned to conveniently enter molded housing recesses 121', 123' at one end thereof, and similarly aligned cover recess (not shown) at its opposite axial end for maintaining the electromagnetic assembly in a desired region of the molded housingll. Magnet arm members 134, 136 transversely extend from the opposed ends of the core 114 and include magnet pole faces 137. A pair of aligned openings 138 are provided in the bobbin side Walls 1164, 118 for pivotally receiving axially extending armature portions 140 for pivotally mounting armature means 125 to the bobbin assembly. It is to be noted that a generally V-shaped air gap is formed intermediate the magnet pole faces 137 and armature member 125. Armature member 125 is biased away from the cooperating pole faces by a leaf spring member having one end 152 thereof secured to the armature adjacent the apex end of the V- gap and the opposite end 154 thereof abutting region 155 of the bobbin.

The armature means 125 further includes an operating portion which generally spans the axial extent between the pole faces 137, and is positioned for movement towards and away from the pole faces, corresponding to sucient electromagnetic actuation of coil 106. As the armature 125 (and particularly operating portion 160 thereof) moves toward the magnet pole faces 137 to close the air gap (shown as a and b in FIGURES 3 and 4, respectively), tripping means portion 127 thereof strikingly engages trip portion 39 of elongated latch means 36, so as to abuttingly move elongated member 36 counterclockwise about its pivot 41. This serves to release the latched engagement of the cradle latch tip 34, and latch means portion 35. This, in turn, permits cradle 31 to rotate clockwise about its pivot 32, under the urging of operating spring 33, and serves to effect tripping disengagement of the circuit breaker contacts 22, 26 in the well known manner.

The air gap separation between the armature operating portion 160 and the magnetic pole faces 137 determines the amount of ux energization required to trip the breaker. That is, a gap separation a, as shown in FIG- URE 3, will require greater electromagnetic energization of coil 106 than gap separation b, shown in FIGURE 4, to pivotally move the armature toward its co-operating pole faces.

My invention advantageously permits an external adjustment of the armature gap while maintaining controlled spacing between the tripping means 127 of the armature and cooperating trip portion 39 of the elongated member. This armature air gap adjustment is obtained by armature adjusting member 60 mounted to the lower end of elongated member 36. Armature adjustment member 60 includes a portion 62, which abuts portion 127 of the armature and serves to move the armature about its pivotal mounting 140, responsive to calibrated movement of screw 74. More specically, inward movement of screw member 74 against tensioning member 80, as shown by arrow 100 of FIGURE 4, rotates the elongated member 36 counterclockwise to the left about its pivot 41 as shown by the arrow 110. This, in turn, moves the lower end of elongated member 36 counterclockwise to the right, as shown by arrow 120. End 62 of resilient adjustment member 60, mounted to the lower end of 36, engages portion 127 of the magnetic trip armature, thereby moving it clockwise about its pivotal mounting 136, 138 so as to reduce the air gap separation from a shown in FIGURE 3 to b shown in FIGURE 4.

Simultaneous with the armature air gap adjustment, the trip portion 39 of elongated member 36, which is strikingly engaged by armature portion 127' responsive to movement of the armature toward its cooperating pole faces, is similarly moved with the lower end of 36 about pivot 41. Therefore, the trip spacing between the armature tripping means 127 and the trip portion 39, shown by the distance d in FIGURES 3 and 4, will be maintained as the armature air gap adjustment is varied. Advantageously, this serves to insure sumcient momentum of the armature at the time it strikes the elongated latching member 36, so as to guarantee a hammer-like blow and safe tripping of the circuit breaker.

By comparing the structure of the instant circuit breaker device, including an eloctromagnetic trip only, to the circuit breaker of my aforementioned U.S. Patent No, 2,996,589, which includes both an electromagnetic and thermal overload tri it should be recognized that my invention utilizes a major portion of the previous thermal calibration to provide the herein desired magnetic trip adjustment. That is, calibration screw 74 had previously been used in conjunction with an elongated member 36 of the bimetallic variety. However, that adjustment did not maintain the magnetic trip latch bite. By the novel the tripping members.

FIGURE 7 refers to a modified form of my invention. External magnetic trip adjustment shown therein includes a button 200, rotatably mounted to outwardly extending lip 212 of the circuit breaker housing. Button 200 includes an internal camming portion 210 in eng-agement with the upwardly extending end 211 of elongated member 36 for rotation of elongated member 36 about its pivot 41, responsive to rotation of button 200. Button 200 may include a slotted head 214 to facilitate the rotation thereof. Button 200 is shown in FIGURE 7 in conjunction with the calibration adjustment 74. Such an arrangement allows the calibration adjustment 74 to be set at the factory for a particular tripping point and then sealed by sealing means 90. Subsequent adjustment in the field may then be provided by button 200. Alternatively, Calibrating adjustment screw 74 and tensioning member 80 may be deleted with the complete range of armature adjustment being provided by button 200.

It is further known that a multiplicity of circuit breaker devices, such as 10, may be positioned side-by-side and interconnected for multi-pole operation. A common trip member (not shown) extends through the aligned apertures 101 of such side-by-side mounted plurality of circuit breaker devices. In the well known manner, the trip member engages elongated members 36 of all the breakers, responsive to a single phase fault to provide simultaneous tripping of all the circuit breakers corresponding to a yfault in one of the poles. My invention lends itself to such multi-pole circuit operation inasmuch as the resiliency of armature adjustment member 60 offers no restriction to the inter-pole trip system when the armature abuts the magnetic pole faces 137.

It is therefore seeen that my invention provides a means for adjusting the magnetic trip within a circuit breaker device in an extremely reliable and simple manner. Further, it is seen that I achieve this advantageous result by a relatively simple modification of a well known prior art circuit breaker device which utilizes a maximum of the previous components and need not necessitate any rework of the housing.

Although in the foregoing my invention has been described in conjunction with preferred embodiments, many variations and modifications will now become apparent to those skilled in the art; and I prefer, therefore, that the instant invention be limited not by the disclosure contained herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. In a circuit breaker comprising:

a stationary contact, a cooperating movable contact, and an operating mechanism for moving said movable contact between contact engaged and contact disengaged conditions with said stationary contact;

said operating mechanism including a latchable member, and a latch means operatively positionable in latching engagement therewith for maintaining said latchable member in a first position;

means for urging said latchable member towards a second position;

said contacts being in said engaged condition corresponding to said latch means maintaining said latchable member in said first position;

said contacts being tripped to said disengaged condition responsive to release of said latching engagement and movement of said latchable member towards said second position;

an electromagnetic trip means for releasing said latching engagement responsive to predetermined circuit conditions;

said electromagnetic trip means including cooperating magnet and armature means;

said armature means normally air gap separated from the pole faces of said magnet means and operatively mounted for movement towards said pole faces to close said air gap;

tripping means moved by said armature means responsive to movement of said armature means towards said pole faces for striking a trip portion of said latch means and causing release of said latching engagement;

means for adjusting the normal air gap separation between said armature means and magnet pole faces, whereby the electromagnetic energization required for moving said armature towards said pole faces is adjustably varied;

said adjustment means including means for simultaneously controlling the trip spacing between said armature tripping means and latch means trip portion, whereby said trip spacing is controlled corresponding to a range of armature air gap adjustments.

2. In a circuit breaker as set forth in claim 1:

said latch means including said trip portion, a first member having a latch portion in engagement with said latchable member, and an armature adjustment portion in engagement with said armature;

said armature air gap adjustment means including a second member for moving said first member, such that said trip portions and armature adjustment portions simultaneously move, thereby simultaneously adjusting the armature air-gap separation while controlling said trip spacing.

3. In a circuit breaker as set forth in claim 1:

a housing for receiving and enclosing said contacts, operating mechanism and electromagnetic trip means;

said adjustment means including a portion extending external of said housing to provide an externally accessible trip adjustment.

4. In a circuit breaker as set forth in claim 2:

said rst member being an elongated member pivotally mounted at an intermediate region thereof;

one end of said elongated member carrying said latch portion, trip portion and armature adjustment portion;

the opposite end of said elongated member being in engagement with said second member.

5. In a circuit breaker as set forth in claim 4:

said armature adjustment portion being a resilient member having a rst portion mounted to said elongated member at one end and a second portion engaging said armature.

6. In a circuit breaker as set forth in claim 4:

a housing for receiving and enclosing said contacts, operating mechanism, electromagnetic trip means first member, said second member including a portion extending external of said housing to provide an externally accessible trip adjustment.

7. In a circuit breaker as set forth in claim 6:

said externally extending portion being a threaded screw, having a rst end projecting towards said elongated member second end, and a second end having a head adapted for external engagement and rotation,

8. In a circular breaker as set forth in claim 6:

said externally extending portion being a button having a first end in camming engagement with said elongated member second end, and a second end adapted for external engagement and rotation.

9. In a circuit breaker as set forth in claim 4:

said trip portion and armature adjustment portion simultaneously moving equal distances responsive to adjustable movement of said second member, such that said trip spacing is maintained corresponding to different armature air-gap adjustment.

References Cited UNITED STATES PATENTS 4/1965 Ziegler 335-42 9/1967 Robins et al. 335-174 

1. IN A CIRCUIT BREAKER COMPRISING: A STATIONARY CONTACT, A COOPERATING MOVABLE CONTACT, AND AN OPERATING MECHANISM FOR MOVING SAID MOVABLE CONTACT BETWEEN CONTACT ENGAGED AND CONTACT DISENGAGED CONDITIONS WITH SAID STATIONARY CONTACT; SAID OPERATING MECHANISM INCLUDING A LATCHABLE MEMBER, AND A LATCH MEANS OPERATIVELY POSITIONABLE IN LATCHING ENGAGEMENT THEREWITH FOR MAINTAINING SAID LATCHABLE MEMBER IN A FIRST POSITION; MEANS FOR URGING SAID LATCHABLE MEMBER TOWARDS A SECOND POSITION; SAID CONTACTS BEING IN SAID ENGAGED CONDITION CORRESPONDING TO SAID LATCH MEANS MAINTAINING SAID LATCHABLE MEMBER IN SAID FIRST POSITION; SAID CONTACTS BEING TRIPPED TO SAID DISENGAGED CONDITION RESPONSIVE TO RELEASE OF SAID LATCHING ENGAGEMENT AND MOVEMENT OF SAID LATCHABLE MEMBER TOWARDS SAID SECOND POSITION; AN ELECTROMAGNETIC TRIP MEANS FOR RELEASING SAID LATCHING ENGAGEMENT RESPONSIVE TO PREDETERMINED CIRCUIT CONDITIONS; SAID ELECTROMAGNETIC TRIP MEANS INCLUDING COOPERATING MAGNET AND ARMATURE MEANS; SAID ARMATURE MEANS NORMALLY AIR GAPS SEPARATED FROM THE POLE FACES OF SAID MAGNET MEANS AND OPERATIVELY MOUNTED FOR MOVEMENT TOWARDS SAID POLE FACES TO CLOSE SAID AIR GAP; TRIPPING MEANS MOVED BY SAID ARMATURE MEANS RESPONSIVE TO MOVEMENT OF SAID ARMATURE MEANS TOWARDS SAID POLE FACES FOR STRIKING A TRIP PORTION OF SAID LATCH MEANS AND CAUSING RELEASE OF SAID LATCHING ENGAGEMENT; MEANS FOR ADJUSTING THE NORMAL AIR GAP SEPARATION BETWEEN THE ARMATURE MEANS AND MAGNET POLE FACES, WHEREBY THE ELECTROMAGNETIC ENERGIZATION REQUIRED FOR MOVING SAID ARMATURE TOWARDS SAID POLE FACES IS ADJUSTABLE VARIED; SAID ADJUSTMENT MEANS INCLUDING MEANS FOR SIMULTANEOUSLY CONTROLLING THE TRIP SPACING BETWEEN SAID ARMATURE TRIPPING MEANS AND LATCH MEANS TRIP PORTION, WHEREBY TRIP SPACING IS CONTROLLED CORRESPONDING TO A RANGE OF ARMATURE AIR GAP ADJUSTMENTS. 